It seems like you feel like since your life is tedious and lonely, it won't be a long one. That doesn't really make sense. Happiness and unhappiness don't directly affect our longevity.
It's more a combination of significantly high stress levels, combined with lifestyle patterns (by necessity, not by choice), Depression, health problems, and a good dollop of pessimism that has built up over many years of having one's face metaphorically pressed into the mud. I've been working to just ride it out, do what I have to do, and then try to live my life (what will be left of it) as I can.